In recent years, as represented by, e.g., vehicles such as hybrid vehicles and electric vehicles, vehicles have been increasingly developed which include a rotating electrical machine as a driving source and have energy efficiency enhanced by converting kinetic energy of the vehicle to electrical energy and collecting the electrical energy by regeneration of the rotating electrical machine.
For example, Japanese Patent Application Publication No. 2008-94253 (JP 2008-94253 A) describes a hybrid vehicle having a rotating electrical machine (motor generator) provided between an engine and a stepped automatic transmission, in which a jumping downshift of the stepped automatic transmission is performed to cause regeneration of the rotating electrical machine at a high rotational speed so that a sufficient regeneration amount is obtained by the rotating electrical machine.
Japanese Patent Application Publication No. 2011-213252 (JP 2011-213252 A) describes that, during power-off shifting, an engagement element to be disengaged is slip-engaged to cause regeneration by a rotating electrical machine.